Virtual Weather Station User's Guide
-27- 03/07/06
6.15.3 Jpeg File Naming Convention
To view the filename for the jpeg image, right-mouse-click
on the weather display and the jpeg filename will be
displayed.
For example, the jpeg filename for the Outdoor
Temperature Spectrum is wc007.jpg
Figure 17 - Jpeg File Settings
6.16 Advanced Parameter Settings
Menu Shortcut: Settings uu Advanced Parameter
Settings
Virtual Weather Station provides the following advanced
parameter settings.
6.16.1 Degree Days Heating and Cooling
Because temperature plays an important part in the rate of
development of plants and many pests, a measurement
which takes into account the accumulation of heat with
passing time is important to predict maturation. Degree-
days provide a measure for calculating the effects of
temperature on the development of plants or pests.
One degree-day is the amount of heat which accumulates
when the temperature remains one degree above the
threshold for one day. One degree day is also the amount
of heat which accumulates when the temperature is 24
degrees above the threshold for one hour.
6.16.1.1 Heating Threshold
The threshold for calculating degree-days heating.
6.16.1.2 Cooling Threshold
The threshold for calculating degree-days cooling.
6.16.2 Wind Run
Wind run is the distance wind has traveled. For example,
the wind run for a constant wind speed of 20 mph for 2
hours is 40 miles, or:
Wind Run = Wind Speed * Time
There may be wind run calculation problems with specific
computers due to the microprocessor and other hardware
devices. If you find the wind run values are out of range,
place the following line in your win.ini file:
wuseDefaultTimer=True
To reset these values, select Settings | Recall Daily,
Monthly and Yearly and edit the windrun for the day,
month and year.
6.16.3 Pressure Trend
Your station may not calculate the pressure trend. Virtual
Weather Station will calculate the pressure trend based on
your own specified threshold. If the rate of change of
pressure is above this threshold, Virtual Weather Station
will report rising pressure. If the rate of change of pressure
is below this threshold, Virtual Weather Station will report
falling pressure.
6.16.4 Wind Gust Calculation
Each weather station uses a different method for calculating
wind gust. You can override your station’s default method
and select the maximum within a specified number of
samples.
6.16.5 Filtered Average Time Constant
The time constant for the filtered average can be varied.
The filter is based on a low pass filter differential equation.
The output value reaches 63% of the input value after one
time constant (the default time constant is 60 minutes or
one hour), and will reach 95% of the input value after five
time constants (default = 300 minutes or five hours).
6.16.6 New Wind Chill Calculation
On November 1, 2001, the National Weather Service
(NWS) implemented a replacement Wind Chill
Temperature (WCT) index for the 2001/2002 winter
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